There are few thousand chemoreceptors in an E.coli cell which exist in the form of dimers [1]}, [2]}. Each receptor dimer can be in two different states: active or inactive. According to Monod-Wyman-Changeux (MWC) model [3]}, [4]}, [5]}, the free energy difference between these two states (in the units of \(K_B T\) ) can be written as
\(\epsilon [ c(x), m] = \log \frac{1+c(x)/K_{min}}{1+c(x)/K_{max}} + \epsilon _0 - \epsilon _1 m\) 
